This invention relates generally to methods of and apparatus for coating fluorescent lamps and, in particular, to methods of and apparatus for coating the glass envelope and a predetermined portion of the end caps of fluorescent lamps.
A fluorescent lamp includes, inter alia, and insofar as pertinent to the present invention, a generally cylindrically shaped glass envelope and end caps provided at either end of the glass envelope and electrical connecting pins provided on the end caps, some lamps have a single pin on each end cap and other lamps have a pair of electrical connecting pins provided on each end cap.
As is known to those skilled in the fluorescent lamp art, a fluorescent lamp upon being dropped or falling from any appreciable height suffers the breakage of the glass envelope into numerous glass shards and, ofttimes, the disassociation of one or more of the end caps from the glass envelope or from the glass shards into which the envelope has broken. Such a happening is always dangerous whenever it occurs as the glass shards may injure a nearby person or a person attempting to handle the broken lamp.
As is further known to those skilled in the fluorescent lamp art and in particular to those experienced in the usage of such fluorescent lamps, for example, in grocery stores or supermarkets, pharmaceutical and food processing plants, hospitals, electronic assembly plants, refrigeration plants where food is stored, such fluorescent lamps are usually mounted quite high on a ceiling or other support and upon their being dropped inadvertently during mounting or replacement, or upon their being caused or allowed to fall by the unintended release of the mounting or supporting means, the fluorescent lamp falls and upon striking virtually any object the glass envelope shatters into thousands of glass shards which can be broadcast into the face and eyes of nearby persons and/or broadcast into foodstuffs such as produce residing on open display counters. Upon such an occurrence, great injury can result to the nearby persons and if all of the glass shards are not removed from the foodstuffs, in particular the produce, persons eating the foodstuffs such as the produce can consume the glass shards and suffer internal injuries including even death. Heretofore the only manner in which to obviate such possibilities is to completely throw away all of the foodstuffs into which the glass shards have fallen or may have potentially fallen which can result in considerable and even great undesirable economic loss.
Accordingly, there exists a great need in the fluorescent lamp art for a protective coating to prevent the above-noted broadcasting of glass shards and economic loss.
More specifically, there exists a great need in the fluorescent lamp art for a coating which may be applied to the fluorescent lamp which does not unduly diminish light emanating from the glass envelope but which upon the glass envelope being shattered will enclose the shattered glass envelope and will maintain the end caps in association with the shattered glass envelope thereby preventing any glass shards from being broadcast about as noted above.
As is further known to those skilled in the fluorescent lamp art, and with regard to those lamps provided with pairs of electrical connecting pins on each end cap and which pairs of pins are in radial alignment, the end caps on some of such lamps are adhesed to the ends of the glass envelope by a heat sensitive adhesive such as a thermoplastic adhesive, and hence upon the application of heat to the fluorescent lamp proximal to the melting point of the adhesive, the end caps tend to loosen and rotate with respect to the glass envelope thereby displacing the pairs of electrical connecting pins out of their radial alignment. Upon cooling of the lamp and readhesing of the heat sensitive adhesive, the pairs of electrical connecting pins are out of radial alignment and the fluorescent lamp is ruined.
Accordingly, there exists a further need in the fluorescent lamp art of being able to maintain the end caps and hence the pairs of electrical connecting pins in radial alignment while the fluorescent lamp and the end caps are heated to a temperature above the melting point of the heat sensive adhesive securing the end caps to the glass envelope.